Vapors (normally known by the name “blow-by gases”) are normally produced in an internal combustion engine, in the heads and/or in the oil tank during the running of the engine itself; air pollution control regulations prohibit exhaust of such vapor into the atmosphere and require that they be fed into the cylinders for controlled combustion thereof. For such reason, an internal combustion engine is provided with a recirculating circuit which is provided with a feed duct originating from the engine head or from the oil tank and connected to an intake duct of the engine.
During routine servicing of the engine, the feed duct may be disconnected from the feed duct and/or engine head for cleaning or replacement or simply to permit easy access to other parts of the engine. Once disconnected from the feed duct and/or engine head, the feed duct may be reconnected poorly due to carelessness on the part of the fitter; such a situation easily goes undetected, by the vapors being released directly into the atmosphere and in no way impairing operation of the engine. For such reason, more recent air pollution regulations require correct connection control of the feed duct and that the driver be alerted of any faulty connection.
One solution to determine the correct connection of the feed duct is described in U.S. Pat. No. 6,532,931-B1, in which the feed duct is provided on the ends with connecting devices; each one of such connecting devices comprises a pneumatic connector for pneumatically connecting the feed duct to the intake duct or engine head, and an electrical connector. Each connecting device is designed so that the relative pneumatic connector is only connected to a corresponding pneumatic connector on the intake duct or engine head when the relative electrical connector is connected to a corresponding electrical connector on the intake duct or engine head; controlling the electrical continuity of the circuit formed by the mutual coupling of the electrical connectors it is possible to check whether the pneumatic connectors are correctly coupled to each other and thereby, it is possible to check the correct connection of the feed duct.
The connection system described in U.S. Pat. No. 6,532,931-B1, however, has some drawbacks in that it employs connecting devices comprising a pneumatic connector and an electrical connector in the same structure, which makes the proper cleaning of the pneumatic connector problematic; moreover, any change in the diameter of the pneumatic connector involves high-cost alteration of the connecting device as a whole.
On the other hand, patent application WO-A1-2004113711 describes a connecting system for the fluid-tight connection between an intake duct and a feed duct which comprises a connecting device, which is adapted to establish a fluid-tight joint between the two ducts and is provided with a fixed electrical connector, a mobile electrical connector, which is mechanically independent of the connecting device and of the second duct and is adapted to couple to the fixed electrical connector. The connecting system also comprises an interlocking device, preferably consisting of elastic spring means, which is adapted to allow the fixed electrical connector and the mobile electrical connector to be coupled to each other, only when there is a fluid-tight joint between the two ducts.
In other words, if the feed duct is not correctly inserted into the dedicated seat of the connecting device, i.e. if there is no fluid-tight joint between the intake duct and the feed duct, the mobile electrical connector cannot be coupled to the fixed electrical connector by the effect of the action of the interlocking device.
However, also the fluid-tight connecting system described in WO-A1-2004113711 has some drawbacks. In fact, it has been determined that the interlocking device may be tampered to allow the mobile electrical connector and the fixed electrical connector to be coupled to each other also when the feed duct is not correctly inserted into the dedicated seat of the connecting device.